<template>
    <div>
       <van-picker :columns="columns" @change="onChange" />
    </div>
</template>
<script>
    const citys = {
  '浙江': [{'杭州':['福州', '厦门', '莆田', '三明', '泉州']}, '宁波', '温州', '嘉兴', '湖州'],
  '福建': ['福州', '厦门', '莆田', '三明', '泉州']
};

export default {
  data() {
    return {
      columns: [
        {
          values: Object.keys(citys),
        //   className: 'column1'
        },
        {
          values: citys['浙江'],
          className: 'column2',
          defaultIndex: 2
        }
      ]
    };
  },
  methods: {
    onChange(picker, values) {
      picker.setColumnValues(1, citys[values[0]]);
    }
  }
};
</script>